Sapphire Ribbons and Apparatus and Method for Producing a Plurality of Sapphire Ribbons Having Improved Dimensional Stability

ABSTRACT

The present disclosure is directed to an apparatus and method for forming sapphire ribbons via Edge-Defined Film-Fed Growth (EFG). Further, the present disclosure is directed to a plurality of concurrently grown sapphire ribbons having features such as a low dimensional variability and elimination of voiding between the sapphire ribbons concurrently grown in a batch.

FIELD OF THE DISCLOSURE

The present disclosure is directed to sapphire ribbons and apparatusesand methods for forming sapphire ribbons particularly by Edge-DefinedFilm-Fed Growth (EFG).

RELATED ART

Sapphire crystals are used in a variety of applications. For example,sapphire ribbons can be used for various demanding, high performancecommercial applications, such as wafers and screen protectors for mobilephones. Further improvement of sapphire ribbons, in particularproduction of a plurality of sapphire ribbons grown concurrently withimproved dimensional stability variation between the ribbons is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example and are not limited in theaccompanying figures.

FIG. 1 includes an illustration of an EFG apparatus according to anembodiment of the present disclosure.

FIG. 2 includes an illustration of an arrangement of dies in an EFGapparatus according to another embodiment of the present disclosure.

FIG. 3 includes an illustration of a sapphire ribbon.

FIG. 4 includes an image of a batch of sapphire ribbons produced in anexample (Batch A).

FIG. 5 includes an image of a batch of sapphire ribbons produced in anexample (Batch B).

FIG. 6 includes an image of a batch of sapphire ribbons produced in anexample (Batch C).

Skilled artisans appreciate that elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help to improveunderstanding of embodiments of the invention.

DETAILED DESCRIPTION

The following description in combination with the figures is provided toassist in understanding the teachings disclosed herein. The followingdiscussion will focus on specific implementations and embodiments of theteachings. This focus is provided to assist in describing the teachingsand should not be interpreted as a limitation on the scope orapplicability of the teachings. However, other embodiments can be usedbased on the teachings as disclosed in this application.

As used herein, the term “C-plane sapphire” refers to substantiallyplanar single crystal sapphire, the C-axis of which is substantiallynormal (±10 degrees) to the major planar surface of the material.Typically, the C-axis is less than about 1 degree from the major planarsurface.

As used herein, the term “A-plane sapphire” refers to substantiallyplanar single crystal sapphire, the A-axis of which is substantiallynormal (±10 degrees) to the major planar surface of the material.Typically, the A-axis is less than about 1 degree from the major planarsurface.

As used herein, the term “R-plane sapphire” refers to substantiallyplanar single crystal sapphire, the R-axis of which is substantiallynormal (±10 degrees) to the major planar surface of the material.Typically, the R-axis is less than about 1 degree from the major planarsurface.

Each of the crystallographic planes in sapphire discussed herein are asis commonly known in the art. It is to be understood that as usedherein, mention of a particular orientation of a crystal sheet to aspecific plane include all off-angle or mis-angle, miscut, or the likeorientations in which the reference plane is tilted to another plane.For example, it is often desirable to product crystal sheets having ageneral A-plane or C-plane orientation, but include a desired tilt ormiscut angle toward the M-plane. Accordingly, use of the phrase“A-plane” or “C-plane” for example, include this plane as the generalreference plane with any desired offcut or misangle orientation.

The following table below illustrates the miller indices and d spacingof the common crystallographic planes in sapphire:

TABLE A Plane Miller Indices d Spacing a (11-20), (-12-10), (-2110)2.379 Å (-1-120), (1-210), (2-1-10) m (10-10), (01-10), (-1100) 1.375 Å(-1010), (0-110), (1-100) c (0001) 2.165 Å r (1-102), (01-12), (-1012)1.964 Å n (11-23), (-12-13), (-2113) 1.147 Å (-1-123), (1-213), (2-1-13)s (10-11), (-1101), (0-111) 1.961 Å

As used herein, the phrases “outer ribbons”, “outer die”, “outersapphire ribbons” , “outer crystal ribbons” and the like include allribbons except the most inner 4 ribbons if the total number of ribbonsbeing concurrently grown is even or the most inner 5 ribbons if thetotal number of ribbons being concurrently grown is odd. For example, inan EFG apparatus adapted to concurrently grow 10 or 11 ribbons, theouter ribbons would include the 3 most outer ribbons on each side.Similarly, and as another example, in an EFG apparatus adapted toconcurrently grow 6 or 7 ribbons, the outer ribbons would include onlythe outermost ribbon on each side.

The terms “comprises,” “comprising,” “includes,” “including,” “has,”“having” or any other variation thereof, are intended to cover anon-exclusive inclusion. For example, a method, article, or apparatusthat comprises a list of features is not necessarily limited only tothose features but may include other features not expressly listed orinherent to such method, article, or apparatus. Further, unlessexpressly stated to the contrary, “or” refers to an inclusive-or and notto an exclusive-or. For example, a condition A or B is satisfied by anyone of the following: A is true (or present) and B is false (or notpresent), A is false (or not present) and B is true (or present), andboth A and B are true (or present).

Also, the use of “a” or “an” is employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one, at least one, or the singular as alsoincluding the plural, or vice versa, unless it is clear that it is meantotherwise. For example, when a single item is described herein, morethan one item may be used in place of a single item. Similarly, wheremore than one item is described herein, a single item may be substitutedfor that more than one item.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The materials, methods, andexamples are illustrative only and not intended to be limiting. To theextent not described herein, many details regarding specific materialsand processing acts are conventional and may be found in textbooks andother sources within the crystal and particularly sapphire crystal arts.

The following disclosure describes apparatuses and methods to form aplurality of sapphire ribbons which have consistent characteristicsbetween each concurrently produced ribbon. For example, it hasheretofore been unknown how to form a multitude of sapphire ribbons, andparticularly at least six sapphire ribbons, having consistency betweenthe ribbons, and particularly the outer ribbons as described herein. Theconcepts are better understood in view of the embodiments describedbelow that illustrate and do not limit the scope of the presentinvention.

FIG. 1 illustrates an apparatus 5 for growing a plurality of crystalribbons 7, in particular a sapphire crystal ribbons, via Edge-DefinedFilm-Fed Growth (EFG) according to a first aspect of the disclosure. Asillustrated in FIG. 1, the apparatus 5 can include a melt source 10; aplurality of dies 20 in communication with the melt source; a pluralityof first regions 30 adjacent the plurality of dies; and a heatreflective shield 50. The heat reflective shield 50 can be angled withrespect to the horizontal plane. The horizontal plane refers to theplane perpendicular to the two vertically extending side surfaces 28 ofthe die tip. As used herein, a heat reflective shield angled withrespect to the horizontal plane includes all orientations other thanperpendicular and parallel with the horizontal plane.

In certain embodiments, the heat reflective shield 50 can be disposedadjacent to at least part of both the die tip 22 and the first region30. The heat reflective shield 50 can include a first surface 52 facingthe die and a second surface 54 opposite the first surface 52. The heatreflective shield 50 can be configured to direct (or reflect) heatenergy contacting the first surface 52 of the heat reflective shieldtowards a region of lower temperature, such as in a second region 32,above the first region 30. Reflecting heat radiating from the firstregion 30 to a region of lower temperature can increase the thermalgradient in the first region 30 above the die relative to an apparatushaving a heat shield parallel to the side surface of the die tip. Assuch, the heat reflective shield 50 can be configured to control a firstthermal gradient from reflected heat in both a lateral direction and avertical direction. This in contrast with a heat shield which isperpendicular to the horizontal plane (or parallel with the side surfaceof the die tip), which reflects most of its heat in the lateraldirection thereby not enabling control of the thermal gradient fromreflected heat in a vertical direction. By angling the heat shield withrespect to the horizontal plane, a significant amount of the radiatedheat can be reflected to an area different from which it originated.

As used herein, “thermal gradient” refers to the average change intemperature of the crystal ribbon over a distance between two locationsin an EFG growth apparatus. The distance between the two locations ismeasured on a line along which the single crystal sapphire advancesduring the production process. For example, in an EFG technique, thetemperature difference may be 50 degrees Celsius between a firstposition in the apparatus and a second position in the apparatus.Thermal gradient units may be, for example, “degrees per cm” or “degreesper inch.” If not specified, the temperature change is from a highertemperature to a lower temperature as the sapphire crystal passes fromthe first location to the second through the gradient. In particularembodiments, the first thermal gradient can extend along the formingplane for a distance of at least about 10 mm, at least about 20 mm, atleast about 30 mm, at least about 50 mm, or even at least about 100 mm.

Further, a second thermal gradient can be located adjacent to the firstthermal gradient. The second thermal gradient can be further away fromthe die opening than the first thermal gradient. In particularembodiments, the second thermal gradient can be less than the firstthermal gradient. For example, as the sapphire ribbon is formed, it canbe cooled faster in the first region 30 than the second region 32 suchthat the second thermal gradient in the second region 32 is less thanthe first thermal gradient in the first region 30.

Referring again to FIG. 1, the plurality of dies can each have a dieopening 24. The die openings 24 can have a width of at least about 101.6mm, at least about 152.4 mm, at least about 203.2 mm, or even at leastabout 304.8 mm. Moreover, in certain embodiments, the die openings 24can have a thickness of at least about 0.3 mm, at least about 0.5 mm, atleast about 1.0 mm, at least about 2.0 mm, or even at least about 2.5mm. The dimensions of the die opening 24 can determine the desireddimensions (width and thickness) of the ribbon formed through the dieopenings. A particular advantage of the present disclosure is theability to form sapphire ribbons with a low variance between dieopenings 24 and the average thickness of each of the sapphire ribbons 7concurrently formed within the same EFG growth apparatus 5. For example,in particular embodiments, a ratio of the average thickness of the outerribbons (and even each of the concurrently produced ribbons) to thethickness of the die opening can be at least about 0.95:1.

Referring now to FIG. 2, there is illustrated a sketch of one embodimentof the arrangement of die openings 25, 27, 29 within an EFG apparatus.As illustrated, the plurality of dies can be arranged such that at leastone of the plurality of die openings 25, 27, 29 are at a differentheight in relation to another one of the plurality of die openings 25,27, 29. For example, the die openings 25 of the outer dies can be higherthan the die openings 29 of the inner dies. Further, the most inner diescan have the lowest die openings 29 of the plurality of die openings 25,27, 29. In certain embodiments, the most outer die openings 25 can havea height which is at least about 0.254 mm, at least about 1.27 mm, atleast about 2.54 mm, or even at least about 3.81 mm higher than the mostnearest adjacent die opening 27.

Further, each of the plurality of dies can be spaced apart from anadjacent die in a horizontal direction of no greater than 609.6 mm, nogreater than 508 mm, no greater than 406.4 mm, no greater than about304.8 mm, no greater than about 254 mm, no greater than about 203.2 mm,no greater than about 152.4 mm, no greater than about 127 mm, no greaterthan about 101.6 mm, no greater than about 76.2 mm, no greater thanabout 50.8 mm, no greater than about 25.4 mm, no greater than about19.05 mm, no greater than about 12.7 mm, or even no greater than about6.35 mm. The spacing is measure from the center of one die tip to thecenter of an adjacent die tip.

Referring again to FIG. 1, the vertical heat shield 55 can be disposedfurther away from angled heat reflective shield 50. In certainembodiments, the EFG apparatus can include both a vertical heat shield55 and the angled heat reflective shield 50. In other embodiments, onlythe angled heat reflective shield 50 may be present.

In certain embodiments, the heat reflective shield 50 can have an anglea with the horizontal plane of no less than about 1 degree, no less thanabout 2 degrees, no less than about 3 degrees, no less than about 4degrees, no less than about 5 degrees, no less than about 10 degrees, noless than about 15 degrees, no less than about 20 degrees, no less thanabout 25 degrees, no less than about 30 degrees, no less than about 35degrees, no less than about 40 degrees, no less than about 45 degrees,no less than about 50 degrees, no less than about 55 degrees, no lessthan about 60 degrees, no less than about 65 degrees, no less than about70 degrees, no less than about 75 degrees, no less than about 80degrees, or even no less than about 85 degrees. In further embodiments,the heat reflective shield can have an angle a of no greater than about88 degrees, no greater than about 85 degrees, no greater than about 80degrees, no greater than about 75 degrees, or even no greater than about70 degrees with horizontal plane. In still further embodiments, the heatreflective shield can have an angle a in a range of any of the maximumand minimum values described herein.

The heat reflective shield 50 can be constructed from any material thatcan manipulate the flow of heat radiation within the EFG apparatus. Incertain embodiments, the heat reflective shield 50 can be constructedfrom a metal, such as for example, a refractory metal.

FIG. 3 illustrates a sketch of a sapphire ribbon 100. The sapphireribbon 100 includes a length L, a width W, and a thickness T. The lengthcan be greater than or equal to the width. The length and the width canbe greater than thickness. It is to be understood that all dimensionalvalues for the one or more ribbons including length, width, thickness,thickness variation, etc. that are described herein are measured on the“virgin” ribbon, i.e. before any finishing operation such as grinding orpolishing, unless expressly stated otherwise. Further, it is to beunderstood that all dimensional values for the one or more ribbonsincluding length, width, thickness, thickness variation, etc. that aredescribed herein are measured for the full width section. As usedherein, the “full width” occurs when the ribbon achieves a width within95% of the width of the die.

In certain embodiments, a sapphire ribbon described herein, and even atleast six or still even all of the concurrently produced sapphireribbons can have a width of at least about 101.6 mm, at least about152.4 mm, at least about 203.2 mm, or even at least about 304.8 mm. Infurther embodiments, a sapphire ribbon described herein, and even eachconcurrently produced sapphire ribbon can have a width of no greaterthan about 2540 mm, no greater than about 1219.2 mm, no greater thanabout 914.4 mm, no greater than about 762 mm, no greater than about609.6 mm, or even no greater than about 457.2 mm. In still furtherembodiments, a sapphire ribbon described herein, and even eachconcurrently produced sapphire ribbon can have a width in a range of anyof the maximum and minimum values described herein.

In further embodiments, a sapphire ribbon described herein, and even atleast six or still even all of the concurrently produced sapphireribbons can have a length of at least about 152.4 mm, at least about304.8 mm, at least about 609.6 mm, at least about 762 mm, at least about914.4 mm, at least about 1066.8 mm, or even at least about 1219.2 mm. Infurther embodiments, a sapphire ribbon described herein, and even atleast six or still even all of the concurrently produced sapphire ribboncan have a length of no greater than about 5080 mm, no greater thanabout 3810 mm, or even no greater than about 2540 mm. In even furtherembodiments, a sapphire ribbon described herein, and even at least sixor still even all of the concurrently produced sapphire ribbons can havea length in a range of any of the maximum and minimum values describedherein.

In still further embodiments, a sapphire ribbon described herein, andeven at least six or still even all of the concurrently producedsapphire ribbons can have an average thickness of at least about 0.1 mm,at least about 0.5 mm, at least about 0.8 mm, at least about 1 mm, atleast about 1.3 mm, at least about 1.5 mm, at least about 1.7 mm, atleast about 2.0 mm, or even at least about 2.3 mm. In furtherembodiments, a sapphire ribbon described herein, and even at least sixor still even all of the concurrently produced sapphire ribbons can havean average thickness of no greater than about 100 mm, no greater thanabout 75 mm, no greater than about 50 mm, no greater than about 35 mm,no greater than about 25 mm, no greater than about 15 mm, no greaterthan about 10 mm, or even no greater than about 5 mm. Further, asapphire ribbon described herein, and even at least six or still evenall of the concurrently produced sapphire ribbons can have an averagethickness within a range between any of the maximum and minimum valuesdescribed herein. As used herein, “average thickness” refers to the meanaverage thickness of all thickness measured in a thickness map havingmeasurements taken every square inch in the full width section. Inparticular, measurements of the thickness and generation of thethickness map can be conducted through ultrasonic measurements as isstandard in the art.

Further, a sapphire ribbon described herein, and even at least six orstill even all of the concurrently produced sapphire ribbons can have atotal thickness variation (TTV) of no greater than 2 mm, no greater than1.8 mm, no greater than 1.6 mm, no greater than 1.4 mm, no greater than1.2 mm, no greater than 1.0 mm, no greater than 0.8 mm, no greater than0.7 mm, no greater than 0.6 mm, no greater than about 0.5 mm, no greaterthan about 0.4 mm, or even no greater than about 0.3mm. Total thicknessvariation is measured by subtraction of the minimum thickness of aribbon from the maximum thickness of a ribbon. As used herein, both theminimum thickness of a ribbon and the maximum thickness can bedetermined by ultrasonic measurement at an interval of 1 measurement persquare inch. In particular embodiments, the TTV can be as describedabove, and if any voids are present, the thickness measurements in andabout the void are not included in the determination of the TTV. Inother words, the minimum thickness, for the purposes of a TTVcalculation, can be the minimum, non-zero thickness. In suchembodiments, any zero measurements determined in the thickness maps arenot used as the minimum thickness for the purposes of a TTV calculation.

Moreover, a particular advantage of the present disclosure is theability to concurrently form a plurality of sapphire, with the outerribbons, at least six ribbons, or even all of the plurality ofconcurrently produced sapphire ribbons have the total thicknessvariation (TTV) described above. Such a characteristic can be quantifiedby the variability of total thickness variation between each of theplurality of concurrently formed sapphire ribbons. The variability oftotal thickness variation can be determined by the following formula:

VTTV=((TTV_(i)−TTV_(AVG))/(TTV_(AVG)))*100%

wherein VTTV represents the variability of total thickness variation;TTV_(i) represents the total thickness variation of the sapphire ribbonof interest and TTV_(AVG) represents the mean average of the totalthickness variation of all concurrently produced sapphire ribbons in abatch. Again, each total thickness variation measurement is determinedby subtracting the minimum thickness value from the maximum thicknessvalue within a ribbon. In particular embodiments, the variability oftotal thickness variation can be no greater than about ±50%, no greaterthan ±40%, no greater than ±30%, no greater than ±15%, no greater thanabout ±10%, no greater than about ±7%, no greater than about ±5%, nogreater than bout ±3%, or even no greater than about ±2%.

In still further embodiments, a sapphire ribbon described herein, andeven at least six or still even all of the concurrently producedsapphire ribbons can have a maximum low spot thickness (or minimumthickness) of at least about 2.0 mm, at least about 1.8 mm, at leastabout 1.6 mm, at least about 1.4 mm, at least about 1.2 mm, at leastabout 1.0 mm, at least about 0.8 mm, at least about 0.7 mm, at leastabout 0.6 mm, or even at least about 0.5 mm. In particular embodiments,a sapphire ribbon described herein, and even at least six or still evenall of the concurrently produced sapphire ribbons can have a maximum lowspot thickness of at least about 1.0 mm, and in even more particularembodiments, at least about 0.5 mm. The maximum low spot thickness is ameasurement of the lowest thickness on the entire sapphire ribbon in themeasurement zone. The maximum low spot thicknesses are measured bystandard techniques for thickness, such as calipers, drop gauges,micrometers, or ultrasound. Moreover, another particular advantage ofthe present disclosure is the ability to concurrently form a pluralityof sapphire ribbons, with the outer ribbons and even all of theplurality of sapphire ribbons having the maximum low spot thicknessdescribed above. A maximum low spot thickness of 0 would indicate a voidpresent in the ribbon.

In still further embodiments, a sapphire ribbon described herein, andeven each concurrently produced sapphire ribbon can have a standarddeviation from planar of no greater than 2 mm, no greater than 1.8 mm,no greater than 1.6 mm, no greater than 1.4 mm, no greater than 1.2 mm,no greater than 1.0 mm, no greater than 0.8 mm, no greater than 0.7 mm,no greater than 0.6 mm, no greater than about 0.5 mm, no greater thanabout 0.4 mm, or even no greater than about 0.3 mm. The standarddeviation from planar is a measurement of the variance from a planarorientation in the sapphire ribbon. The standard deviation from planarcan be measured by standard techniques for thickness, such as calipers,drop gauges, micrometers, or ultrasound. Moreover, another particularadvantage of the present disclosure is the ability to concurrently forma plurality of sapphire ribbons, with the outer ribbons and even all ofthe plurality of sapphire ribbons having the standard deviation fromplanar described above.

A particular advantage of the present disclosure is the ability toconcurrently form a plurality of sapphire ribbons, where each of theplurality of sapphire ribbons, and particularly the outer ribbons areessentially free of voids. As used herein, “voids” refers to a defect ina single crystal ribbon in which there is a gap or aperture within theribbon. Further, as used herein, “essentially free of voids” refers to asingle crystal ribbon in which there is no discontinuation of sapphireacross the width of the crystal, that is the crystal has a thicknessgreater than 0. It has heretofore been unknown how to concurrently forma plurality of sapphire ribbons, where each of the sapphire ribbons isessentially free of voids. For example, as will be described in moredetail below in the EXAMPLE section, adding dies to a traditional EFGapparatus produced crystal ribbons on the outer dies with substantialvoiding and inconsistent dimensional stability. Without wishing to belimited by theory, it is believed that in a traditional EFG growthapparatus, the temperature and the thermal gradient on the outer ribbonsis different than the inner ribbons. It is believed that theinconsistent thermal gradient between ribbons may cause defects such asvoiding and variation in total thickness variation, particularly in theouter ribbons. Accordingly, in certain embodiments described herein,each concurrently formed sapphire ribbon can be essentially free ofvoids, and in particular embodiments, the outer ribbons, at least sixribbons, or even all of the concurrently produced ribbons can beessentially free of voids.

According to another embodiment of the present disclosure, a method ofconcurrently forming a plurality of sapphire ribbons can includeproviding an EFG apparatus having a plurality of dies; crystallizing theplurality of ribbons, particularly sapphire ribbons above each of theplurality of dies; and cooling the plurality of sapphire ribbons.Cooling the plurality of sapphire ribbons can include controlling afirst thermal gradient in a first region adjacent the die andcontrolling a second thermal gradient in a second region adjacent thefirst region and further away from the die than the first region. Thesecond thermal gradient can be lower than the first thermal gradientsuch that the ribbons are cooled faster in the first region than in thesecond region. The thermal gradients in the first or second region canbe partially controlled with a heat reflective shield. In certainembodiments, the heat reflecting shield can be angled with respect tothe horizontal plane as described above.

A particular advantage of the present disclosure is the ability tocontrol the first and second thermal gradients (most importantly thefirst thermal gradient) such that the thermal gradients are consistentor have a low variability between the plurality of sapphire ribbons. Forexample, in a traditional EFG growth apparatus, it has not been possibleto control the first thermal gradient such that each of the firstthermal gradients in each of the concurrently formed sapphire ribbonsare greater than about 1.5° C./cm, greater than about 2° C./cm, greaterthan about 3° C./cm, greater than about 5° C./cm, 10° C./cm, greaterthan about 20° C./cm, greater than about 50° C./cm, greater than about100° C./cm, greater than about 200° C./cm, greater than about 500° C./cmor even greater than about 1000° C./cm.

In particular embodiments, the sapphire ribbons can have a dwell time ofat least about 10 minutes in the first region. As used herein, “dwelltime” refers to the length of time a point on the ribbon spends within aregion of the EFG apparatus. As discussed above, the first region isbetween the die opening and the second region.

In an EFG apparatus, the plurality of ribbons are “pulled” from the meltand crystallized above the die to form the ribbons. The rate at whichthe ribbons are pulled from the melt is referred to the draw rate. Incertain embodiments, the draw rate of each of the plurality of ribbonscan be the same or at least one can be different. In particularembodiments, the sapphire ribbons can be drawn at a rate of 0.5 cm/hr,1.0 cm/hr, 1.5 cm/hr, 2.0 cm/hr, 2.5 cm/hr, at least 5 cm/hr, or even atleast 10 cm/hr.

As used herein, “spread” or “spreading” refers to the forming of thewidth dimension of the crystal ribbon during crystallization andcooling. Without wishing to be bound by theory, it is believedcontrolling the thermal gradients can, in part, control the spreading ofthe crystal ribbon. A particular advantage of the present disclosure isthe ability to achieve a consistent spread width between each of theplurality of sapphire ribbons produced in a batch.

Further in certain embodiments, the method can include controlling thespread length of the plurality of crystal ribbons such that theplurality of crystal ribbons have a maximum spread length variability ofno greater than about 25%, no greater than about 20%, no greater thanabout 18%, no greater than about 15%, no greater than about 10%, or evenno greater than about 5%. As used herein, “spread length” refers to thedistance between the seed and the full width section. Maximum spreadlength variability is determined by the following equation:

SLV_(MAX)=((SL_(MAX)−SL_(MIN))/((SL_(MAX)+SL_(MIN))/2))*100%

wherein SLV_(MAX) refers to the maximum spread length variability;SL_(MAX) refers to the maximum spread length of one of the plurality ofsapphire ribbons produced in a batch; and SL_(MIN) refers to the minimumspread length of one of the plurality of sapphire ribbons produced in abatch. A particular advantage of the present disclosure is the abilityto achieve a consistent spread length between the plurality of sapphireribbons produced in a batch.

According to certain embodiments, the plurality of sapphire ribbonsproduced by the methods described herein can have the characteristicsdescribed herein such as the total thickness variation, variability oftotal thickness variation, maximum low spot thickness, standarddeviation from planarity, etc. A particular advantage of the presentdisclosure is the ability to concurrently form a plurality of sapphireribbons, with each of the sapphire ribbons have the characteristicsdescribed herein. In particular, the method described herein can be usedto concurrently form at least 3, at least 4, at least 5, at least 6, atleast 7, at least 8, at least 9, at least 10, at least 11, at least 12,at least 13, at least 14, at least 15, or even at least 16 sapphireribbons, where each of the ribbons has the characteristics describedherein. Further, in certain embodiments, the method described herein canbe used to concurrently for no more than 50, no more than 25, or even nomore than 20 sapphire ribbons in the same growth apparatus.

In fact, it has never before been possible to concurrently produce 6 ormore sapphire sheets in the same growth apparatus with each ofconcurrently produced ribbons having the dimensional stability describedherein. Accordingly, certain embodiments described herein are directedto producing 6 or more ribbons, wherein at least 6 of the 6 or moreribbons have the characteristics described herein, such as totalthickness variation and variability of total thickness variation.

Furthermore, embodiments of the present disclosure are further directedto a batch of sapphire ribbons. As used herein, a “batch” refers to aplurality of sapphire ribbons concurrently (simultaneously) formed inthe same growth apparatus. For example, a batch can include at least 3,at least 4, at least 5, at least 6, at least 7, at least 8, at least 9,at least 10, at least 11, at least 12, at least 13, at least 14, atleast 15, or even at least 16 sapphire ribbons that are concurrentlyformed in the same growth apparatus. Further, in certain embodiments, abatch can include no more than 50, no more than 25, or even no more than20 sapphire ribbons that are currently formed in the same growthapparatus.

In particular embodiments, each of the sapphire ribbons in the batch canhave the characteristics described herein such as total thicknessvariation, variability of total thickness variation, maximum low spotthickness, standard deviation from planarity, be essentially free ofvoids, etc. A particular advantage of the present disclosure is theability to form a batch of sapphire ribbons, with each of the sapphireribbons in the batch having the characteristics described herein.

The sapphire ribbons described herein can be further processed to form amultitude of various products. In particular embodiments, the sapphireribbons can be cut to form wafers, and particularly a batch of wafers.As used herein a “batch of wafers” refers to wafers formed from aplurality of concurrently formed sapphire ribbons. Moreover, in stillfurther embodiments, a light emitting device can be formed from thewafer, or a plurality of light emitting devices can be formed from thebatch of wafers.

In even further embodiments, a protector screen for mobile devices canbe formed from the sapphire ribbon described herein. The formation ofthe protector screen can be performed according to any method known inthe art.

In even further embodiments, a transparent window that transmits in thevisible spectra may be formed from the sapphire ribbon described herein.

The EFG apparatus, and the sapphire ribbons produced therefrom can haveany desired crystal orientation. In certain embodiments, the sapphireribbons can have a C-axis, an A-axis, an R-axis, a M-axis, a N-axis, oran S-axis orientation substantially perpendicular to the sapphireribbon's major surface. In certain particular embodiments, the sapphireribbons can have a C-axis, an A-axis, or an R-axis orientationsubstantially perpendicular to the sapphire ribbon's major surface. Inparticular embodiments, the sapphire ribbons have a C-axis orientationsubstantially perpendicular to the sapphire ribbon's major surface. Inother particular embodiments, the sapphire ribbons have an A-axisorientation substantially perpendicular to the sapphire ribbon's majorsurface. The crystal orientation can be determined by seeding a meltfixture with a seed having known, desired orientation substantiallyperpendicular to a longitudinal axis of a die opening. The thus formedribbon will then have a corresponding orientation substantiallyperpendicular to the sapphire ribbon's major surface.

EXAMPLES Example 1

Three batches of C-plane sapphire ribbons and one batch of A-planeribbons were produced. The first batch (Batch A; C-plane) was producedusing an EFG growth apparatus depicted in FIG. 1 except with a verticalheat shield. The second batch (Batch B; C-plane) was produced using theEFG growth apparatus depicted in FIG. 1 with a heat shield have an angleof 62 degrees with the horizontal plane. A third batch (Batch C;C-plane) was produce using the same EFG growth apparatus for Batch Bexcept the height of the most outer dies was lowered by 0.635 mm and thedies adjacent the most outer dies was raised by 0.635 mm. The fourthbatch (Batch D; A-plane) was produced using the same EFG growthapparatus as Batch C except that an A-plane sheet was grown using a seedorientated in the A-plane. Each apparatus was configured with 10 diesand each run produced a batch of 10 C-plane or A-plane sapphire ribbons.All other conditions parameters for growth were identical except forminor adjustments to accommodate A-plane growth.

For each of the batches, the crucible and die is heated until the top ofthe die is greater than 2100 degrees C. Alumina pellets are loaded intothe crucible through a tube that extends outside of the furnace and isprotected by an inert atmosphere, such as argon. Once the melt level ishigher than about half of the die height, a seed having a C-axis (orA-axis for A-plane) orientation perpendicular to the growth direction islowered to the die tips. The temperature of the die is lowered, and theseed is pulled vertically away from the die at a rate of 27.94 mm/hr.The temperature is controlled as function of the mass. Once the crystalis at full width, and the temperature remains constant until the desiredlength has been achieved.

Various characteristics of each of the sapphire ribbons in the batcheswere measured and the following results were obtained:

TABLE 1 Property Batch A Batch B Batch C Batch D Mean Average Length434.34 mm 457.2 mm 609.6 mm   760 mm Mean Average Width 157.48 mm 147.32mm  157.48 mm  157.48 mm  (after spreading) Mean Average Thickness2.5146 mm 2.4892 mm  2.667 mm 2.819 mm Maximum Thickness 2.9718 mm2.8956 mm  2.8956 mm  3.023 mm Minimum Thickness    0 mm 2.159 mm 2.0828mm  2.540 mm Maximum Width 157.48 mm 157.48 mm  157.48 mm  157.48 mm Minimum Width 157.48 mm 139.7 mm 157.48 mm  157.48    Maximum Total2.7178 mm 0.6096 mm  0.381 mm 0.406 mm Thickness Variation Mean AverageTotal 0.7112 mm 0.381 mm 0.254 mm 0.254 mm Thickness Variation MaximumVariance in 2.5654 mm 0.4826 mm  0.254 mm 0.406 mm Total ThicknessVariation Maximum Spread   254 mm   254 mm 203.2 mm 208.3 mm Length(ribbon #1) (ribbon #7) (#8,9) (#9) Minimum Spread Length  177.8 mm152.4 mm 152.4 mm 152.4 mm (ribbon #4,5,6) (ribbon #1,10) (#4,5,6) (#2,#5) Maximum Spread  76.2 mm 101.6 mm  50.8 mm  50.8 mm LengthVariability Presence of Voids in Yes No No No Outer Ribbons

Each of the thickness measurements and values discussed in Table 1 aboveare determined from a generated thickness map. To produce the thicknessmap, the thickness of the ribbon is measured every square inch andmapped on an image of the ribbon as described in more detail above andunderstood by one of ordinary skill in the art. The table aboveindicates that Batch C resulted in the best results with the mostconsistency in the dimensional control between the C-plane sapphireribbons. Batch D indicates that A-plane ribbons also benefit from thechanges incorporated in the die for Batch C, as results similar to BatchA would be obtained for A-plane ribbons using the Batch A dieconfiguration.

Pictures of each of the C-plane sapphire ribbons were taken on graphpaper to show dimensions of the ribbons and thickness maps of each ofthe ribbons were produced. FIG. 4 illustrates a photograph of each ofthe ribbons produced in Batch A. FIG. 5 illustrates a photograph of eachof the ribbons produced in Batch B; FIG. 6 illustrates a photograph ofeach of the ribbons produced in Batch C. Voids were visually apparent inthe outer dies of Batch A, but no voids existed in the ribbons of BatchB or C.

Example 2

The same apparatus and method provided for Batches C and D above wereused in an EFG growth apparatus with 16 dies. Similar results to thatachieved with Batches C and D were present in the sapphire sheets, andparticularly the outer sapphire sheets, when growing 16 concurrentsapphire sheets.

Many different aspects and embodiments are possible. Some of thoseaspects and embodiments are described below. After reading thisspecification, skilled artisans will appreciate that those aspects andembodiments are only illustrative and do not limit the scope of thepresent invention. Embodiments may be in accordance with any one or moreof the items as listed below.

Item 1. An apparatus for forming a sapphire ribbon via Edge-DefinedFilm-Fed Growth (EFG), the apparatus comprising a heat reflective shieldangled with respect to a horizontal plane, wherein the heat reflectiveshield is configured to control a thermal gradient from reflected heatin a lateral direction and a vertical direction.

Item 2. An apparatus for concurrently forming at least six sapphireribbons, wherein at least six of the at least six sapphire ribbons areessentially free of voids.

Item 3. An apparatus for concurrently forming at least six sapphireribbons, wherein at least six of the at least six sapphire ribbons havean average width of at least 101.6 mm.

Item 4. An apparatus for forming a sapphire ribbon, the apparatuscomprising:

-   -   a melt source;    -   a die adjacent the melt source;    -   a first region adjacent an opening of the die; and    -   a heat reflective shield adjacent at least a portion of the die        and at least a portion of the first region, wherein the heat        reflective shield comprises a first surface facing the die and a        second surface opposite the first surface, wherein the heat        reflective shield is configured to direct heat energy contacting        the first surface of the heat reflective shield towards a region        of lower temperature.

Item 5. An apparatus for concurrently forming at least six ribbonscomprising sapphire, the apparatus comprising:

-   -   a melt source;    -   at least six dies adjacent the melt source, wherein each die has        a length and a width;    -   at least three first regions adjacent each opening of the at        least three dies, wherein the at least three first regions have        a width and a thickness corresponding to a width and thickness        of the die opening, and wherein each of the at least three first        regions has a corresponding first thermal gradient across the        thickness of the first region, and wherein each of the at least        three first thermal gradients have a temperature gradient of at        least 1.5 ° C./min.

Item 6. A method of concurrently forming at least six ribbons comprisingsapphire, the method comprising:

-   -   crystallizing the at least six ribbons of crystal above at least        six dies, and    -   cooling the at least six ribbons of crystal in a first region        adjacent the at least six dies, wherein cooling comprises        controlling a thermal gradient across a thickness of the at        least six ribbons of crystal such that each of the at least six        ribbons have a total thickness variation of no greater than 5%        after cooling has finished.

Item 7. A method of concurrently forming at least six ribbons comprisingsapphire, the method comprising:

-   -   a. crystallizing the at least six ribbons above at least six        dies, and    -   b. controlling the spread length of each of the sapphire ribbons        such that a maximum spread length variability of at least six of        the at least six ribbons is no greater than about 25%.

Item 8. A batch of at least six concurrently EFG grown sapphire ribbons,wherein at least six of the at least six EFG grown sapphire ribbons havea total thickness variation of no greater than 10%.

Item 9. A batch of at least six concurrently EFG grown sapphire ribbons,wherein at least six of the at least six EFG grown sapphire ribbons inthe batch are essentially free of voids.

Item 10. A batch of at least six concurrently EFG grown sapphireribbons, wherein at least six of the at least six EFG grown sapphireribbons in the batch have a maximum spread length variability of nogreater than about 20%.

Item 11. A batch of at least six concurrently EFG grown sapphireribbons, wherein at least six of the at least six EFG grown sapphireribbons in the batch have an average width of at least 101.6 mm.

Item 12. A sapphire ribbon grown from an outer die in an EFG growthapparatus configured to simultaneously produce at least six sapphireribbons, wherein the sapphire ribbon grown from the outer die have athickness variation within 10% of the average thickness of each of thesapphire ribbons produced simultaneously with the sapphire ribbons grownfrom the outer dies.

Item 13. A crystal ribbon grown from an outer die in an EFG growthapparatus configured to simultaneously produce at least eight crystalribbons, wherein the crystal ribbon is essentially free of voids.

Item 14. A wafer cut from an outer sapphire crystal ribbon grownconcurrently with at least 6 sapphire crystal ribbons.

Item 15. A light-emitting device made from the sapphire wafer of item14.

Item 16. A sapphire protector screen for mobile devices formed from anouter crystal ribbon grown concurrently with at least 6 crystal ribbons.

Item 17. The apparatus, method, batch or ribbon of any one of thepreceding items, wherein the crystal ribbons have an average width of atleast about 101.6 mm, at least about 152.4 mm, at least about 203.2 mm,or even at least about 0.304.8 mm.

Item 18. The apparatus, method, ribbon, or batch of any one of thepreceding items, wherein the crystal ribbons have an average length ofat least about 152.4 mm, at least about 304.8 mm, at least about 609.6mm, or even at least about 762 mm.

Item 19. The apparatus or method of any one of the preceding items,wherein the heat reflective shield is angled with respect to a formingplane.

Item 20. The apparatus, method, ribbon, or batch of any one of thepreceding items, wherein the one or more sapphire ribbons have anaverage thickness of at least about 0.1 mm, at least about 0.5 mm, atleast about 0.8 mm, at least about 1 mm, at least about 1.3 mm, at leastabout 1.5 mm, at least about 1.7 mm, at least about 2.0 mm, or even atleast about 2.3 mm.

Item 21. The apparatus, method, ribbon, or batch of any one of thepreceding items wherein the one or more sapphire ribbons have an averagethickness of no greater than about 100 mm, no greater than about 75 mm,no greater than about 50 mm, no greater than about 35 mm, no greaterthan about 25 mm, no greater than about 15 mm, no greater than about 10mm, or even no greater than about 5 mm.

Item 22. The apparatus, method, ribbon, or batch of any one of thepreceding items, wherein each sapphire ribbon has a Total ThicknessVariation of no greater than 2 mm, no greater than 1.8 mm, no greaterthan 1.6 mm, no greater than 1.4 mm, no greater than 1.2 mm, no greaterthan 1.0 mm, no greater than 0.8 mm, no greater than 0.7 mm, no greaterthan 0.6 mm, no greater than about 0.5 mm, no greater than about 0.4 mm,or even no greater than about 0.3 mm

Item 23. The apparatus, method, ribbon, or batch of any one of thepreceding items, wherein each sapphire ribbon has a Total ThicknessVariation of no greater than 2 mm, no greater than 1.8 mm, no greaterthan 1.6 mm, no greater than 1.4 mm, no greater than 1.2 mm, no greaterthan 1.0 mm, no greater than 0.8 mm, no greater than 0.7 mm, no greaterthan 0.6 mm, no greater than about 0.5 mm, no greater than about 0.4 mm,or even no greater than about 0.3 mm, and wherein the TTV is determinedwithout including any voids.

Item 24. The apparatus, method, ribbon, or batch of any one of thepreceding items, wherein the variability of total thickness variationbetween the total number of concurrently formed ribbons can be nogreater than about ±50%, no greater than ±40%, no greater than ±30%, nogreater than ±15%, no greater than about ±10%, no greater than about±7%, no greater than about ±5%, no greater than bout ±3%, or even nogreater than about ±2%.

Item 25. The apparatus, method, ribbon, or batch of any one of thepreceding items, wherein each sapphire ribbon has a maximum low spotthickness of at least about 2.0 mm, at least about 1.8 mm, at leastabout 1.6 mm, at least about 1.4 mm, at least about 1.2 mm, at leastabout 1.0 mm, at least about 0.8 mm, at least about 0.7 mm, at leastabout 0.6 mm, or even at least about 0.5 mm.

Item 26. The apparatus or method of any one of the preceding items,wherein the heat reflective shield forms an angle with a forming planeof no greater than about 85 degrees, no greater than about 80 degrees,no greater than about 75 degrees, or even no greater than about 70degrees.

Item 27. The apparatus or method of any one of the preceding items,wherein the heat reflective shield forms an angle of no less than about1 degrees, no less than about 2 degrees, no less than about 3 degrees,no less than about 4 degrees, no less than about 5 degrees, no less thanabout 10 degrees, no less than about 15 degrees, no less than about 20degrees, no less than about 25 degrees, no less than about 30 degrees,no less than about 35 degrees, no less than about 40 degrees, no lessthan about 45 degree, no less than about 50 degrees, no less than about55 degrees, or even no less than about 60 degrees.

Item 28. The apparatus or method of any one of the preceding items,wherein the heat reflective shield comprises a metal, in particular arefractory metal.

Item 29. The apparatus or method of any one of the preceding items,wherein the heat reflective shield is positioned such that a significantportion of heat radiating laterally from the first region is reflectedtoward an area of lower temperature.

Item 30. The apparatus or method of any one of the preceding items,wherein the heat reflective shield is disposed adjacent to the firstregion.

Item 31. The apparatus or method of any one of the preceding items,wherein the first thermal gradient extends along the forming plane for adistance of at least about 1 cm, at least about 2 cm, at least about 3cm, at least about 5 cm, or even at least about 10 cm.

Item 32. The apparatus or method of any one of the preceding items,further comprising a second thermal gradient adjacent to the firstthermal gradient, wherein the second thermal gradient is further awayfrom the die opening than the first thermal gradient, and wherein thesecond thermal gradient is less than the first thermal gradient.

Item 33. The apparatus or method of any one of the preceding items,wherein the die opening has a width of at least 25.4 mm, at least 50.8mm, at least 76.2 mm, at least 101.6 mm, at least 152.4 mm, or even atleast 203.2 mm.

Item 34. The apparatus or method of any one of the preceding items,wherein the die opening has a thickness of at least 0.3 mm, at least 0.6mm, at least 0.75 mm, at least about 1 mm, at least about 1.5 mm, atleast about 2 mm, at least about 2.5 mm, at least about 2.8 mm, at leastabout 3 mm, or even at least about 3.5 mm.

Item 35. The apparatus or method of any one of the preceding items,wherein a ratio of the average thickness of the sapphire ribbon to thethickness of the die opening is at least about 0.95:1.

Item 36. The method of any one of the preceding items, wherein the dwelltime of a specific point on the sapphire ribbon in the first region isat least 10 minutes.

Item 37. The method of any one of the preceding items, furthercomprising drawing the sapphire ribbon at a rate of at least 0.5 cm/hr,at least 1.0 cm/hr, at least 1.5 cm/hr, at least 2.5 cm/hr, at least 5cm/hr, or even at least 10 cm/hr.

Item 38. The apparatus or method of any one of the preceding items,wherein the outer die openings are disposed higher than at least one dieopening between the outer die openings.

Item 39. The apparatus or method of any one of the preceding items,wherein at least one die openings is disposed at a different height thanthe other die openings.

Item 40. The apparatus, method, batch, or ribbon of any one of thepreceding items, wherein the one or more sapphire ribbons have a C-axis,an A-axis, M-axis or an R-axis orientation substantially perpendicularto the sapphire ribbon's major surface.

Item 41. The apparatus, method, batch, or ribbon of any one of thepreceding items, wherein the one or more sapphire ribbons have a C-axisorientation substantially perpendicular to the sapphire ribbon's majorsurface.

Item 42. The method of any one of the preceding items, furthercomprising seeding a melt fixture with a seed having an A-axis, aC-axis, M-axis or a R-axis orientation substantially perpendicular to alongitudinal axis of a die opening; and wherein the sapphire ribbon hasa corresponding A-axis, C-axis, M-axis or R-axis orientationsubstantially perpendicular to the sapphire ribbon's major surface.

Item 43. The method of any one of the preceding items, furthercomprising seeding one or more melt fixtures with a seed having a C-axisorientation substantially perpendicular to a longitudinal axis of a dieopening; and wherein the one or more sapphire ribbons have acorresponding C-axis orientation substantially perpendicular to the oneor more sapphire ribbon's major surface.

Item 44. A batch of at least six concurrently EFG grown sapphireribbons, wherein at least six of the at least six EFG grown sapphireribbons have a total thickness variation of no greater than 10%.

Item 45. A batch of at least six concurrently EFG grown sapphireribbons, wherein at least six of the sapphire ribbons in the batch areessentially free of voids.

Item 46. The batch of any one of the preceding items, wherein at leastsix of the sapphire ribbons in the batch have an average width of atleast about 101.6 mm.

Item 47. The batch of any one of the preceding items, wherein at leastsix of the sapphire ribbons in the batch have an average length of atleast about 152.4 mm.

Item 48. The batch of any one of the preceding items, wherein at leastsix of the sapphire ribbons in the batch have an average thickness in arange of from about 0.1 mm to about 100 mm.

Item 49. The batch of any one of the preceding items, wherein at leastsix of the sapphire ribbons in the batch have a Total ThicknessVariation (TTV) of no greater than 2 mm.

Item 50. The batch of any one of the preceding items, wherein twosapphire ribbons grown from outer dies in the batch have a TotalThickness Variation (TTV) of no greater than 1.2 mm.

Item 51. The batch of any one of the preceding items, wherein at leastsix of the sapphire ribbons in the batch have a Total ThicknessVariation (TTV) of no greater than 2 mm, and wherein the TTV isdetermined without including any voids.

Item 52. The batch of any one of the preceding items, wherein at leastsix of the sapphire ribbons in the batch have a Total ThicknessVariation (TTV) of no greater than 1.2 mm, and wherein the TTV isdetermined without including any voids.

Item 53. The batch of any one of the preceding items, wherein thevariability of total thickness variation between the total number ofconcurrently formed ribbons is no greater than about ±50%.

Item 54. The batch of any one of the preceding items, wherein thevariability of total thickness variation between the total number ofconcurrently formed ribbons is no greater than about ±10%.

Item 55. The batch of any one of the preceding items, wherein each ofthe at least six of the at least six EFG grown sapphire ribbons have atotal thickness variation of no greater than 5%.

Item 56. The batch of any one of the preceding items, wherein at leastsix of the sapphire ribbons in the batch have a maximum low spotthickness of at least about 1 mm.

Item 57. The batch of any one of the preceding items, wherein at leastsix of the sapphire ribbons in the batch have a maximum low spotthickness of at least about 0.5 mm.

Item 58. The batch of any one of the preceding items, wherein the one ormore sapphire ribbons in the batch have a C-axis, an A-axis, M-axis oran R-axis orientation substantially perpendicular to the sapphireribbon's major surface.

Item 59. The batch of any one of the preceding items, wherein the one ormore sapphire ribbons have an A-axis orientation substantiallyperpendicular to the sapphire ribbon's major surface.

Item 60. The batch of any one of the preceding items, wherein the batchcomprises at least 8 sapphire ribbons.

Item 61. The batch of any one of the preceding items, wherein the batchcomprises at least 10 sapphire ribbons.

Item 62. A sapphire ribbon grown from an outer die in an EFG growthapparatus configured to simultaneously produce at least six sapphireribbons, wherein the sapphire ribbon grown from the outer die has athickness variation within 10% of the average thickness of each innersapphire ribbon produced simultaneously with the sapphire ribbon grownfrom the outer die.

Item 63. The sapphire ribbon of item 62, wherein the sapphire ribbongrown from an outer die is essentially free of voids.

Note that not all of the activities described above in the generaldescription or the examples are required, that a portion of a specificactivity may not be required, and that one or more further activitiesmay be performed in addition to those described. Still further, theorder in which activities are listed is not necessarily the order inwhich they are performed.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any feature(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature of any or all the claims.

The specification and illustrations of the embodiments described hereinare intended to provide a general understanding of the structure of thevarious embodiments. The specification and illustrations are notintended to serve as an exhaustive and comprehensive description of allof the elements and features of apparatus and systems that use thestructures or methods described herein. Separate embodiments may also beprovided in combination in a single embodiment, and conversely, variousfeatures that are, for brevity, described in the context of a singleembodiment, may also be provided separately or in any subcombination.Further, reference to values stated in ranges includes each and everyvalue within that range. Many other embodiments may be apparent toskilled artisans only after reading this specification. Otherembodiments may be used and derived from the disclosure, such that astructural substitution, logical substitution, or another change may bemade without departing from the scope of the disclosure. Accordingly,the disclosure is to be regarded as illustrative rather thanrestrictive.

What is claimed is:
 1. A batch of at least six concurrently EFG grownsapphire ribbons, wherein at least six of the at least six EFG grownsapphire ribbons have a total thickness variation of no greater than10%.
 2. A batch of at least six concurrently EFG grown sapphire ribbons,wherein at least six of the sapphire ribbons in the batch areessentially free of voids.
 3. The batch of claim 1, wherein at least sixof the sapphire ribbons in the batch have an average width of at leastabout 101.6 mm.
 4. The batch of claim 1, wherein at least six of thesapphire ribbons in the batch have an average length of at least about152.4 mm.
 5. The batch of claim 1, wherein at least six of the sapphireribbons in the batch have an average thickness in a range of from about0.1 mm to about 100 mm.
 6. The batch of claim 1, wherein at least six ofthe sapphire ribbons in the batch have a Total Thickness Variation (TTV)of no greater than 2 mm.
 7. The batch of claim 1, wherein two sapphireribbons grown from outer dies in the batch have a Total ThicknessVariation (TTV) of no greater than 1.2 mm.
 8. The batch of claim 1,wherein at least six of the sapphire ribbons in the batch have a TotalThickness Variation (TTV) of no greater than 2 mm, and wherein the TTVis determined without including any voids.
 9. The batch of claim 1,wherein at least six of the sapphire ribbons in the batch have a TotalThickness Variation (TTV) of no greater than 1.2 mm, and wherein the TTVis determined without including any voids.
 10. The batch of claim 1,wherein the variability of total thickness variation between the totalnumber of concurrently formed ribbons is no greater than about ±50%. 11.The batch of claim 1, wherein the variability of total thicknessvariation between the total number of concurrently formed ribbons is nogreater than about ±10%.
 12. The batch of claim 1, wherein each of theat least six of the at least six EFG grown sapphire ribbons have a totalthickness variation of no greater than 5%.
 13. The batch of claim 1,wherein at least six of the sapphire ribbons in the batch have a maximumlow spot thickness of at least about 1 mm.
 14. The batch of claim 1,wherein at least six of the sapphire ribbons in the batch have a maximumlow spot thickness of at least about 0.5 mm.
 15. The batch of claim 1,wherein the one or more sapphire ribbons in the batch have a C-axis, anA-axis, M-axis or an R-axis orientation substantially perpendicular tothe sapphire ribbon's major surface.
 16. The batch of claim 1, whereinthe one or more sapphire ribbons have an A-axis orientationsubstantially perpendicular to the sapphire ribbon's major surface. 17.The batch of claim 1, wherein the batch comprises at least 8 sapphireribbons.
 18. The batch of claim 1, wherein the batch comprises at least10 sapphire ribbons.
 19. A sapphire ribbon grown from an outer die in anEFG growth apparatus configured to simultaneously produce at least sixsapphire ribbons, wherein the sapphire ribbon grown from the outer diehas a thickness variation within 10% of the average thickness of eachinner sapphire ribbon produced simultaneously with the sapphire ribbongrown from the outer die.
 20. The sapphire ribbon of claim 19, whereinthe sapphire ribbon grown from an outer die is essentially free ofvoids.